GlossaryEN1 min readUpdated: Jun 18, 2026

UN Number

Unlike a hazard class, which describes a category of danger, a UN Number uniquely identifies a hazardous substance or group of substances with global validity.

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Last updated: 18 June 2026Published: 22 November 2025

Source: https://unece.org/transport/dangerous-goods

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Logistics Concept

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Definition & Explanation

Unlike a hazard class, which describes a category of danger, a UN Number uniquely identifies a hazardous substance or group of substances with global validity. The four-digit code – for example UN 1203 for petrol or UN 1090 for acetone – is assigned by the United Nations Committee of Experts on the Transport of Dangerous Goods and applies regardless of the transport mode or the countries involved. It must appear on dangerous goods transport documents, orange placards, packages, and containers. Shippers, freight forwarders, and drivers must reference the UN Number across all modes – road (ADR), rail (RID), sea (IMDG), and air (ICAO/IATA DGR) – as it forms the basis for emergency response and regulatory inspections. Not to be confused with the CAS number, which identifies individual chemical substances for scientific purposes and carries no transport-law significance.

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UN Number

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